Dump truck



Aug. 27, 1963 H. M. RoBRTsoN E rAL DUMP TRUCK Filed Jan. 9, 1961 4Sheets-Sheet' 1 30 'UMH-f" FIG-1 FIG-2 INVENToRs HANEY M. ROBERTSON etBY JAMES E lNGLE M M V55/ ATTORNEYSA H. M. ROBERTSON E-r AL 3,101,974

Aug. 27, 1963 DUMP TRUCK 4 Sheets-Sheet 2 Filed Jan. 9, 1961 FIG -6PowER TAKE oFF Aug- 27, 1963 H. M. ROBERTSON ETAL 3,101,974

4DUMP TRUCK 4 Sheets-Sheet 3 Filed Jan. 9, 1961 INVENTORS HANEY M.ROBERTSON 8| BY JAMES E. INGLE Mwmy ATTORNEYS Allg- 27, 1963 H. M.R-oBERTsQN Erm. 3,101,974

DUMP TRUCK 4 Sheets-Sheet 4 Filed Jan. 9, 1961 FIG -8 PowER TAKE oFFUnited States Patent OliFice 3|,l0l,974 Patented Aug. 27, 1963 3,101,974DUMP TRUCK Haney M. Robertson and James E. Ingle, Tell City, Ind.,

assignors to Maxon Construction Company, Inc., Dayton, hio, acorporation of Ohio Filed Jan. 9, 1961, Ser. No. 81,563

4 Claims. (CL 23S-17.6)

This application relates to dump trucks for conveying and dumping owablematerials, particularly for conveying and dumping freshly mixedconcrete.

In the art of concrete paving, particularly, a well known systemfollowed by contractors who 'are paving great lengths of pavement, suchas roadways, runways, etc., involves the use of a central mixing plantin which the concrete is mixed, and from which it is transported to thepaving site and then spread and finished by machinery operating over theroadbed. One suitable type of spreader for use in this fashion is shownin copending application Serial No. 733,949, ytiled May 8, 1958, nowPatent No. 3,043,201, assigned to the same assignee as this application,in which a spreader bucket is mounted on a frame for traversing movementacross the roadway, and in which the frame operates along the forms forthe roadway, using them as rails, such that a load placed in thespreader bucket may be distributed in a ribbon transversely of theroadbed, and the machine then moved forward to prepare for spreading thenext ribbon of concrete.

Such a spreading machine is capable of relatively high speed operation,in this art, but the bucket has a rather large capacity, for exampleupto six cubic yards of fresh vconcrete, and in order for this machine tooperate rapidly, and thus with the 'best etliciency, it is necessary tosupply the fresh concrete to the bucket at a rate concomitant with its:best-operating speed. The present invention provides a dump truck whichis capable of performing this function.

In accordance with the invention, dump trucks are provided having tdumpbodies which dump to either side of the truck frame or chassis, and thuspermit the trucks to be driven along the side of the roadway directlyinto position opposite the spreading machine, to dump the load directlyand rapidly into the spreading machine bucket, and to pull away with theleast possible disruption of routine, 'and with minimum amount of timerequired. Thus, the dump body is required to handle approximately sixyards of fresh concrete, which will weigh in the neighborhood of twelvetons, and to dump this entire load olf to either side of the truck,without disrupting the truck chassis or Without the necessity for anyexternal bracing or temporary support tosteady the truck chassis duringthe dumping operation.

Accordingly, the primary object of this invention is to provide a noveldump truck body construction capable of dumping large heavy loads olf toeither side of the truck body, without the need for external support, bymaintaining the'center of gravity of the loaded dump bucket, during theinitial portion of the dumping operation, essentially in line withthelongitudinal center line of the truck frame, thus preventing anyexcessive side force which would tend to topple the truck, with the loadgradually being diminished as it is dumped overboard.

Another object of this invention is to provide such a novel side dump'body in which gate constructions are incorporated tending to controlthe dumping of the load in such 3a Way as to facilitate the maintenanceof the center of gravity of the load adjacent the center line of thetruck body until the load is essentially discharged.

Another object of this invention is to provide a side dump truck bodywherein the axis about which the load carrying bucket is rotated duringa dumping operation is i loca-ted to one sideof the truck yframe andwell above the center point or longitudinal central axis of thel dumpbody, requiring that the bucket be lifted up and about its pivot pointand thus` maintaining the center of gravity of the loaded bodyessentially adjacent to the center -line of the truck during the initialportions of the dumping opera-tion.

A further object lof this invention is to provide a novel mounting 'forsuch a side du-mp body in which alternate pivot points are providedwhich may receive hinge pins for the dump bucket, providing yfor dumpingthereof toward either side of the truck chassis.

An additional object of this invention is to provide a dump truck body,particularly adapted for transporting and dumping fresh concrete, inwhich there is a relatively high discharge point for dumping thematerial laterally over one side of the truck chassis, whichincorporates a novel gate construction which opens rapidly toward itslfull extension as the dump bucket is lifted initially, and which doesnot require any special chute or like construction to direct theconcrete into a spreader bucket or the like.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings land the appendedclaims.

In the drawings- FIG. 1 is a side elevational View of a dump body inaccordance with the invention, ywith portions of a truck cab, frame, andwheels shown in dotted lines;

FIG. 2 is a view of the dump body per se, viewing the rear thereof, asfrom 'the right end of FIG. l, with portions broken away and shown insection, and with parts of the hydraulic control and power system shownschematically;

FIG. 3 is a partial sectional view on a slightly enlarged scale, showingthe manner in which the bucket rests normally upon the lower baseportion of the body, and showing also the location of the hydraulicreservoir;

FIG. 4 is a View similar to FIG. 2, with the bucket shown in full linesin a partly raised position, and shown in `dotted lines in a somewhatdifferent Araised position, with a segment of a spreader bucket locatedto one side of the truck chassis, which is sho-wn in dotted lines;

IFIG. 5 is a view similar to FIG. 4, showing the dump bucket in itsfully raised or extended position, and showing also the locations of thecenter `of gravity as the bucket is raised;

FIG. 6 is a schematic diagram of a suitable hydraulic system forcontrolling movement of the dump bucket;

FIG. 7 is a view similar to FIG. 4, showin-g a modification of theinvention, wherein lthe discharge ygate is provided with a Ipower drivefor opening and closing thereof, independent .of the pivoting or dumpingmovement of the bucket; and

FIGS. 8 and 9 are schematic diagrams of suitable bydraulic systems fusedin connection with the modied construction shown in FIG. 7.

Referring to the drawings, which illustrate a preferred embodiment o-fthe invention, and particularly with reference to FIGS. l, 2 and 3, atruck body is provided adapted for mounting Iupon a truck frame 10 ofany suitable construction, rearwardly of the cab 112 thereof, andinwardly above the rear load bearing axles and wheels, of 'which thereare usually two sets in beavy duty trucks of this type, indicated by thegeneral reference numeral 14. The truck body includes ia bed or framewhich is provided by a pair yofl'lorizontally extending beams l15- andreinforcing platforms 17, which may actually be part of the truck fenderconstruction, extending beyond the opposite sides thereof together with'gusset or reinforcing .plates 19 which are suitably welded in place, inthe position shown.V At the forward and rearward end of this bedconstruction,

which is ,generally open along the middle as shown in FIG. 3, there areprovided mounting means for the dump bucket indicated by the generalreference numeral 2t), and such mounting means are provided by generallyV-shaped support arms, each of which extends toward opposite sides ofthe bed, and thereabove, as shown in FIGS. 2, 4 and 5.

Each of the mounting and supporting `arms is of reinforced double walledconstruction, and includes at each of its upper arm ends hinge pinbearings and 26, respectively, and the mounting arms are so aligned uponthe bed that the bearings 25 and 26 are `aligned front to rear to definepivot axes extending parallel to the length of the bed substantiallyabove the main lframe thereof. Each `arm of the mounting members alsoincludes an extension plate or support Z7 which provides a mounting fora pivotally `arranged guiding link 28, with the link pivoting about itsfixed mounting on the plate 2.7.

The load carrying dump bucket is indicated by the general referencenumeral 30, yand is likewise of generally V-shape in cross-section, andof essentially the same crosssection throughout its length, terminatingin rfront and rear end walls 31 and 32. The bucket is relatively deepwith respect to its width, for example the depth `at its center isgreater than one-half its -greatest width (near the top of the endwalls) yand the center depth may be about three-quarters -of thegreatest width, as `shown in the drawings. Sockets 33 (one shown in FIG.5) are provided in the end walls of the dump bucket for alignment withthe hinge pin bearings 25 and 26, respectively, and hinge pins 35 `-areinserted on one side only, as selected, to provide a pivotal mounting ofthe dump bucket for a dumping movement thereof about the chosen pivotaxis which is located above the side lip of the bucket over which thecontents tare discharged, as seen particularly in FIGS. 2 and 4. Thehinge pins preferably may be selectively placed in either of thebearings 25 or 26 and received accordingly in the corresponding socketsin the dump body, to change the dumping :action of the bucket from oneside to the other of the dump body.

The dump body normally rests in its load carrying position with thelower central portion thereof extending between the beams 15 formingpart of the bed (lFIG. 3) and this arrangement provides a convenientsupport for the load carrying bucket 30. The dump bucket also isprovided with suitable reinforcing gusset plates or like structure,shown at 37, to strengthen the bucket, since in one convenient size ofconstruction this bucket may be dimensioned to carry up to six cubicyards of fresh wet concrete weighing in the neighborhood of twelve tons.

Power pivoting movement of lche dump bucket is provided by linear actinghydraulic motors 40 of the piston cylinder type, one being locatedwithin each of the supporting larrn structures Iat the forward andrearward ends of the bed. In a preferred construction the cylindricalportion of the motor is pivotally mounted in a bearing 42 to the bedstructure, and the piston rod 43 is pivotally connected at 44 to theappropriate end wall of the bucket through reinforcing plates 45. Thus,`as is described hereinafter, actuation of these motors will :cause apivoting dumping action of the bucket `about the inserted hinge pins 35.

In order to assure that the load is dumped rapidly beyond the selectedside of the dump body, -gate members 50 are provided, each pivotallyconnected to the upper edge or side lip of the bucket structure per se,Kas by suitable piano-type hinge members 52 (FIGS. l `and 2). The gatewhich is located on the side closest tothe selected pivot taxis, wherethe binge pins `are inserted, is in turn pivotally connected at 53 tothe outer end of the guiding and controlling link 28, and the locationsof the pivot points between length 2S and plate 27 as well as the hinge52 land the pivot connections 53 kare so related dimensionally that -asthe bucket 30 is raised in :a pivoting movement about the binge pins 35the gate 50 will swing open with an initially accelerated motion suchthat the load wil-l pass rapidly over the gate to be dumped at the sideof the truck. Each gate includes wings 54 functioning to preventmaterial from flowing off the side edges of the gate when it is opened.

This quick opening action of the gate is particularly Shown bycomparison of the dotted and full line positions shown in FIG. 4 withthe linal raised position of the dump body, and the relative position:of the gate, as shown in FIG. 5. It will be Iapparent from inspectionof the drawings that by the time that the bucket is raised approximatelyhalf way through its dumping motion, as shown in the full line portionof FIG. 4, the opening gate 50 is well beyond a lhalf way open positionwith respect to dump body 30, and by the time the body is raised to itsfull dump position shown in FIG. 5, the motion of the -gate has retardedsuch that the gate surface is substantially copla-nar with the adjacentsloping interior surface yof the dump body. The lgate not being used isheld in its closed or raised position :by pins 55 which can also betransferred for use with either gate.

Accordingly, particularly with reference to FIG. 5, as the loaded bucketis raised through its dumping motion, the lip adjacent hinge pins 35moves downwardly and inwardly toward the center of the bed. The centerof gravity of the loaded bucket, indicated approximately at 56 in FIG.5, will move essentially vertically along, and initially somewhat to theopposite side of, the 'longitudinal vertical vcenter plane of the `dumpbody, the load will be dissipated by reason of the dumping action overthe quickly opened gate 50 such that the center of gravity of the dumpbucket, now empty as shown in FIG. 5, will be approximately at 57, andthe total lateral deviation of the center of gravity of the bucket willbe within the limits indicated at a in FIG. 5. It will be noted that atno time does the center of gravity of the dump bucket move beyond thepivot axis thereof, nor beyond the track dimensions of the truck wheels.Furthermore, the center of gravity of the fully loaded body, at rest andduring the initial portion of the dumping action is maintainedessentially at the center of the bed and below the pivot axis, and theforces tending to tip the truck yduring dumping are thus substantiallyminimized. In actual practice, it bas been observed that there is noapparent tipping action of any consequence upon the truck as a wholeduring dumping of a full load of approximately twelve tons of material.

'For example, referring particularly to FIG. 5, the verticallongitudinal center plane of the `truck body is indicated by thedot-dash line 60. As noted previously, the center of gravity of thelloaded bucket is indicated at 56. When the dump bucket is fully raisedthe center of gravity of the entire dump truck body, including thebucket and supporting frame, deviates to the left of this center planeapproximately by the distance b as shown in FIG. 5, yand this results inla deviation of the center of ygravity of the entire truck and dump bodycombination, with the dump bucket raised, of the relatively slightdistance c. 'Ibercfore, it will be seen that the total deviation of thecenter of gravity of a truck equipped with a dump body in accordancewith the invention is relatively slight, and will not produce anysignificant force tending to topple the truck.

FIG. 6 illustrates a typical hydraulic power drive for controllingmovement of the dump bucket. The hydraulic motors 40 (normally calledhydraulic cylinders in practice) are connected in parallel to supplylines 65 `and 66. The power takeoff from the truck engine, shownschematically in FIG. 6, is connected to operate a positive displacementpump 68, and this pump draws hydraulic fluid 'from reservoir 70 throughline 72 and supplies this uid through line y75 for direction to eitherof the lines 65 or 66, depending upon the manipulation of a manuallycontrolled 3way valve which is shown schematically at 78.

' In its center position .this valve will close ott` the lines 65 and 66from the supply and provide a dump or Kbypass connection from pump 68.Thus the bucket will be retained at whatever position it occupies whenthe 4valve is so closed. In its other two positions this valve willalternately direct fluid under pressure to lines 66 or 65, to raise orto controlthe lowering of the dump bucket 30. The opposite line will`:at the same time be connected, in conventional fashion, Ito an exhaustor tank line 79 whichwill returnY fluid to reservoir 70. Also, aconventional relief valve 80 is connected between lines 75 and 79 torelieve excessive pressure in line 75, should this ever develop. Thelocation of the elements of the hydraulic system are sho-wn generally inFIG. 2, wherein it will be noted that lines 65 and 66 include flexiblehose sections 65o and 66a accommodating the necessary pivotal motion ofthe hydraulic motors during actuation thereof. Pump 68 may beconveniently mounted at the rear of one of the beams 15, and thereservoir 70 maybe suitably mounted in the space :between these beams,as shown in FIG. 3.

It is also possible to use a simplified hydraulic powerv and controlsystem wherein single y acting cylinders are employed instead ofthedouble Iacting ones 40, thus providing power only to'dump and relyingupon gravity for lowering the emptied bucket. This will result in asimpler hydraulic system with Kfewer lines Iand connections, and will beobvious to those skilled in the art.

The modified construction shown in FIGS. 7 land 8 is simil-ar to thearrangement previously described in many respects. Accordingly, similarreference numerals 4in the 'l00-series `are applied to parts which areidentical in operation and yfunction to corresponding parts previouslydescribed. Not all of these parts are mentioned specifically hereafter,but it will be understood that they correspond to the above describedconstruction with-out specic reference thereto. v Y

Accordingly, in FIG. 7 the Idump bucket 131i is shown as pivotallymounted on hinge pins 135 which in turn are carried at `the top` of thesupporting arm structure120. The bucket is swung between its carryingposition and its dumping position by the hydraulic cylinders 140, ofwhich there is one at each lend of the bucket, and the gate member 150is hinged to the side of the bucket at 152. At the upper edge of thebucket construction there is a bracket or mounting plate 155 whichprovides a pivotal mounting for a hydraulic gate control cylinder 157,and the piston rod 158 of this cylinder is pivotally connected at 159 toigate 150.

Referring to FIG. 8, the pump 168 may be driven vby the power take-olffrom the truck engine, and supplies hydraulic fluid under pressure fromthe tank or reservoir l170 to the supply line 172. vThe main or bucketcontrol cylinders 140 are shown as of the singleaoting type, and thesupply and exhaust of hydraulic fluid thereto is under the control ofthe manually operated 3-position valve 175, which has three differentinternal passage arrangements as shown. Connected to this bucket drivecircuit, which includes the pressure fluid supply line 165 and theexhaust or drain line 166, is a circuit for the Igate drive cylinders157, it being runderstood that there is one of these cylinders arrangedat each end of the Igate 150. These cylinders are show-n as of thedouble-acting type, and the hydraulic :fluid is supplied thereto throughcontrol line 180, and` exhausted through line 181. Line 180 is connectedto the pressure supply line 165 through an internal connection in tvalve 175, in each position thereof, and supplies pressure fluid to amanually operable 3-way valve 185. Preferably, valves 175 and 185 areprovided as a single unit in actual practice, having a single manualcontrol lever. However, :for simplification of illustration they areshown as individual valves. It should be understood, however, that thereare commercially available valve units which provide all the necessaryfunctions of these two valves 6 in a single unit, whichis indicatedschematically by the dotted lines in lFIG. 8.

This, when the pressure fluid is supplied to the bucket motors orcylinders 140, line 180 is simultaneously connected to the pressurefluid supply line, and the cylinders 157 operate to open gate 150simultaneously with the dumping action of the bucket. lt has been foundthat in actual practice, due to the resistance provided by the load onthe main cylinders 14th that the hydraulic circuit will inherentlyfunction to supply pressure fluid to cylinders 157 acting 'to cause aquick opening of gate as the bucket 130 is raised, in essentially thesame manner as previously described in connection with the mechanicallinkage construction shown in FIGS. 2, 4 and 5. 'I'f the cylinders 157are found to open too rapidly in relation to the buckets dumping motion,the operation of these cylinders can be retarded by employing a line 180of lower capacity, or otherwise throttling the iiow of pressure lluid tothese cylinders.

VThe foregoing description, with respect to the system shown in FIG. 8,assumes that the operator'will manipulate the manual controls for thevalves and `185, andr probably that these controls will be on the truckbody, for example to the rear thereof as shown in FIG. 2. Itrmay bedesirable in some instances to provide a remote control :for operationof the dump body, for example by push button operation-"from the truckcab so that the driver can control the entire dumping operation withoutleaving the cab. In such an arrangement, a convenient system can beprovided in accordance with the apparatus shown in FIG. 9, wherein thevalves A175e and 1850: are of the same type as valves 175 and 185,respectively, as relgards internal porting and passages.

These valves, however, are normally self-centered by springs -orv theequivalent (not shown) and each may be shifted in one direction or theother by pilot controls. For purposes of explanation, such pilotcontrols are shown as remotely controlled solenoids, the solenoids l19t)and 191 being energized simultaneously by closing ofswitch 192, to movethese valves to a position supplying pressure fluid to swing rthe dumpbucket to its discharging position and to open the gate. Similarly,closing of switch 195 will energize solenoids 196 and 197 to shift thesevalves in the opposite direction and thus to return the emptied dumpbucket to its normal carrying position and to close the gate. These pushbutton switches can be of the spring-opened type which require theoperator to hold the button depressed in order to close the switch andoperate the system, and of course such switches `can be convenientlymounted in the cab for manipulation by the driver.

The yforegoing description assumes the desirability of providing a d-umpbody which can be connected to dump to either side, as described. 0fcourse, if at the time of construction it has already been determinedthat the body is to dump only to one side, then the supporting arms 20can be constructed with only one arm, instead of the V-shaped armconstruction shown. With such an arrangement all operating parts wouldbe the same as described previously, except that the dump body would ofcourse discharge only to the side toward which such modi-fied armsextend to provide the high point pivot mounting.

Accordingly, the present invention provides a novel d-ump body fortrucks and the like which is readily adapted to standard truck chassisor to similar conveyance chassis, and which maintains the center ofgravity closely adjacent to the longitudinal center line of the bodysuch that no additional or temporary supporting structure is needed toaccommodate `shifting of load during the dumping operation. The presentinvention also provides `a dump body in which dumping can beaccomplished there -is very little metering of the load through smalldischange chutes or members during the dumping operation.

While the form of apparatus herein 'described constit'utes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of appaartus, and that changes maybe made therein without departing trom the scope of the invention whichis `defined in the appended claims.

What is claimed is:

l. A dumping body comprising a rectangular bed adapted for mounting on achassis with its longer dimension extending front to back of saidchassis and its shorter dimension centered on said chassis, a load-carrying dump bucket of generally symmetrical configuration about a verticalplane extending longitudinally through its center and along the longerdimension of said bed, opposed upwardly and divergently extending sideson said bucket extending angularly with respect to said central plane ofsaid bucket, front and rear `end Walls on said bucket connected to saidsides and projecting upwardly above said sides, at least one of saidsides terminating in a lip extending essentially the full length thereofand located substantially below the top of said end walls, a gate hingedto said bucket adjacent said lip and extending the full length of saidlip and projecting upward therefrom in the load-carrying position ofsaid bucket, means forming an upward extension from lthe other of saidsides to at least the top of said end walls, said sides and said endwalls together with said gate and said extension forming means dening aload-carrying enclosure which has a depth along its said central planeof more than one-half the width of said bucket at its greatest widthdimension adjacent its top', mounting means for said bucket positioningit on said bed with its said central plane centered with respect to saidbed in load-carrying position, pivot means included in said mountingmeans and attached to said bucket dening a pivot axis extending parallelto and spaced above said lip and located substantially closer to saidlip than to said central plane of said bucket, said pivot axis beingabove the center of gravity of said bucket when said bucket is in itsload-carrying position with a load therein, power dumping means actingon said bucket for causing pivotal movement thereof about saidpivot'axis to cause said `lip to mov-e downwardly and inwardly and tocause the center of gravity of the loaded bucket to remain near to saidcentral plane until after the material begins to discharge over saidlip, and means for opening said gate during dumping motion of saidbucket to carry material discharged over said lip outwardly over saidgate beyond the side of said bed.

2. A dump body as defined in claim 1 wherein said extension meanscomprises an additional gate hinged to said other side of said bucket,and additional pivot means included in said mounting means and forming apivot axis along said other side of said bucket'arranged parallel ywithrespect to said rst mentioned pivot means, means for selectively andalternatively causing one of said pivot means to be operative and theother to be inoperative, and controls for said gates also alternativelyand selectively operable to open during a dumping operation only thatgate over which the load is being discharged.

3. A dump body as dened in claim 1, including a linkage pivotallyVconnected to said gate and to said mounting means 4for causingpredetermined opening movement of said gate in response to dumpingmovement of said bucket.

4. A dump body as dened in claimv l, including power operated meansoperably connected to said gate, and a control for said power operatedmeans for causing opening movement of said gate during dumping movementof said bucket.

References Cited in the tile of this patent UNITED STATES PATENTS1,852,618 LeTourneau Apr. 5, 1932 1,983,280 Flowers Dec. 4, 19342,194,068 Eisenberg Mar. 19, 1950 2,812,210 Osborn Nov. 5, 19572,872,787 Flowers Feb. l0, 1959

1. A DUMP BODY COMPRISING A RECTANGULAR BED ADAPTED FOR MOUNTING ON ACHASSIS WITH ITS LONGER DIMENSION EXTENDING FRONT TO BACK OF SAIDCHASSIS AND ITS SHORTER DIMENSION CENTERED ON SAID CHASSIS, A LOAD-CARRYING DUMP BUCKET OF GENERALLY SYMMETRICAL CONFIGURATION ABOUT A VERTICALPLANE EXTENDING LONGITUDINALLY THROUGH ITS CENTER AND ALONG THE LONGERDIMENSION OF SAID BED, OPPOSED UPWARDLY AND DIVERGENTLY EXTENDING SIDESON SAID BUCKET EXTENDING ANGULARLY WITH RESPECT TO SAID CENTRAL PLANE OFSAID BUCKET, FRONT AND REAR END WALLS ON SAID BUCKET CONNECTED TO SAIDSIDES AND PROJECTING UPWARDLY ABOVE SAID SIDES, AT LEAST ONE OF SAIDSIDES TERMINATING IN A LIP EXTENDING ESSENTIALLY THE FULL LENGTH THEREOFAND LOCATED SUBSTANTIALLY BELOW THE TOP OF SAID END WALLS, A GATE HINGEDTO SAID BUCKET ADJACENT SAID LIP AND EXTENDING THE FULL LENGTH OF SAIDLIP AND PROJECTING UPWARD THEREFROM IN THE LOAD-CARRYING POSITION OFSAID BUCKET, MEANS FORMING AN UPWARD EXTENION FROM THE OTHER OF SAIDSIDES TO AT LEAST THE TOP OF SAID END WALLS, SAID SIDE AND SAID ENDWALLS TOGETHER WITH SAID GATE AND SAID EXTENSION FORMING MEANS DEFININGA LOAD-CARRYING ENCLOSURE WHICH HAS A DEPTH ALONG ITS SAID CENTRAL PLANEOF MORE THAN ONE-HALF THE WIDTH OF SAID BUCKET AT ITS GREATEST WIDTHDIMENSION ADJACENT ITS TOP, MOUNTING MEANS FOR SAID BUCKET POSITIONINGIT ON SAID BED WITH ITS SAID CENTRAL PLANE CENTERED WITH RESPECT TO SAIDBED IN LOAD-CARRYING POSITION, PIVOT MEANS INCLUDED IN SAID MOUNTINGMEANS AND ATTACHED TO SAID BUCKET DEFINING A PIVOT AXIS EXTENDINGPARALLEL TO AND SPACED ABOVE SAID LIP AND LOCATED SUBSTANTIALLY CLOSERTO SAID LIP THAN TO SAID CENTRAL PLANE OF SAID BUCKET, SAID PIVOT AXISBEING ABOVE THE CENTER OF GRAVITY OF SAID BUCKET WHEN SAID BUCKET IS INITS LOAD-CARRYING POSITION WITH A LOAD THEREIN, POWER DUMPING MEANSACTING ON SAID BUCKET FOR CAUSING PIVOTAL MOVEMENT THEREOF ABOUT SAIDPIVOT AXIS TO CAUSE SAID LIP TO MOVE DOWNWARDLY AND INWARDLY AND TOCAUSE THE CENTER OF GRAVITY OF THE LOADED BUCKET TO REMAIN NEAR TO SAIDCENTRAL PLANE UNTIL AFTER THE MATERIAL BEING TO DISCHARGE OVER SAID LIP,AND MEANS FOR OPENING SAID GATE DURING DUMPING MOTION OF SAID BUCKET TOCARRY MATERIAL DICHARGE OVER SAID LIP OUTWARDLY OVER SAID GATE BEYONDTHE SIDE OF SAID BED.